Multi-level analysis of low-cost Z-pinned composite joints: Part 2: Joint behaviour

In the framework of the E-U program ALCAS (Advanced Low-Cost Aircraft Structure), a new Z-pinning technique was developed by EADS Innovation Works. This technology was used to manufacture low-cost Z-pinned junction demonstrators (L and T shaped specimens) typical of aeronautical structures. In order to understand load transfer mechanisms in this kind of assembly, a multi-level analysis was performed. In the first part of this study, tension and shear pin behaviour was investigated as well as pin pull-out from neat resin or laminate. An analytical model was proposed to predict the maximum load capability of a single pin for an insertion depth of less than 8 mm which correspond to the usual technology. Now, in this second part, we demonstrate that the behaviour of the junction under pull-out, shear and unfolding is globally homothetic to the mechanical behaviour of a pin. This study provides the basis for a pre-sizing methodology for Z-pinned junctions under complex loading.